[kogepathic]

> Maybe I'm missing something obvious?

There are many different package managers depending on which Linux you're running.

Debian and derivatives use apt, Red Hat uses yum or dnf, SuSE uses yast, Gentoo has emerge, Arch has pacman... So each package manager needs to build their own package and it's easier to recompile from source than slice and dice a binary.

Also distributions will install the binaries, shared libraries, man pages, etc to different locations (some to /usr, some to /use/local, etc) which is also easier to define at configuration since most autoconf/make files support this already.

Finally they might want to add patches for distribution specific features or quirks. Or maybe they compile with ulibc instead of glibc.

There are many valid reasons why distributions would and should take the upstream source and build/package it themselves.